Mometasone furoate, one of the steroids used for treating allergic rhinitis, is known to be highly effective in prolonged symptom-relief. Azelastine hydrochloride, one of the short-acting antihistamines, is known to be highly effective in immediate symptom-improvement. Therefore, co-administration of these two drugs in a combination formulation is expected to exhibit an excellent effect in the long-term treatment of allergic rhinitis, along with immediate symptomatic improvement.
International Publication WO97/01337 has disclosed a nasal spray or nasal drop formulation comprising azelastine or its salt; and beclomethasone, flunisolide, triamcinolone, dexamethasone or budesonide. And also, International Publication WO2003/105856 has disclosed a pharmaceutical formulation suitable for nasal or ocular administration (e.g., a nasal spray), which comprises azelastine or its salt; and a steroid such as mometasone furoate.
Meanwhile, azelastine hydrochloride has strong bitter taste. The degree of the bitter taste is so intense that it is even found to be unpleasant in a dilution of 1×106 time (U.S. Pat. No. 5,164,194). After azelastine hydrochloride is intranasally applied, such a bitterness of azelastine hydrochloride is delivered to the pharynx, thereby causing unpleasant taste and irritation. U.S. Pat. No. 6,576,677 has disclosed a use of polyvinylpyrrolidone and/or copolyvidone for alleviating the unpleasant taste of azelastine hydrochloride. And also, International Publication WO2006/058022 has disclosed a pharmaceutical composition comprising azelastine hydrochloride and mometasone furoate, wherein sucralose is used as an agent for masking bitterness.